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GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST Large Area Telescope: Mechanical Systems WBS: 4. 1. 8 Section 13 Marc Campell SLAC Mechanical Systems Manager [email protected] stanford. edu Document: LAT-PR-01967 Section 13 Mechanical Systems 1

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Overview Section 13. 1 Section 13 Mechanical Systems 2

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems Organization Document: LAT-PR-01967 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems Organization Document: LAT-PR-01967 Section 13 Mechanical Systems 3

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Subsystems Overview Grid Assembly GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Subsystems Overview Grid Assembly Assy Grid Box Base Assy Grid Box Mid-Plate +Z X-LAT Plate EMI Shields Radiator Mount Brkt HPPP DSHP Document: LAT-PR-01967 Section 13 Mechanical Systems 4

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major Subassemblies • Grid Assembly GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major Subassemblies • Grid Assembly – 4 x 4 Grid + Radiator Mount Brackets • Grid Box Base Assembly (GBBA) – Grid Assy + Top Flange & Downspout HP + HP Patch Panel – Configuration delivered to I & T for LAT integration • Grid Box Assembly – GBBA + EMI Skirt + X-LAT & Mid-plates – Mechanical Systems Top Assembly test configuration – Static Load and Thermal Cycle tests • Radiators – Fabricated and tested by LM • X-LAT and Mid-plates – Fabricated and tested by LM Document: LAT-PR-01967 Section 13 Mechanical Systems 5

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Placement +Z GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Placement +Z Document: LAT-PR-01967 +Z Section 13 Mechanical Systems 6

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design & Fabrication Responsibilities Manufacturing/Integration GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design & Fabrication Responsibilities Manufacturing/Integration Activity Grid Assembly Fabricate, inspect Grid structure Fabricate, test Top Flange heat pipes Fabricate, test Downspout heat pipes Assemble, test Grid assembly Fabricate, inspect EMI Skirt parts X-LAT Thermal Plate Fabricate, inspect X-LAT Plate parts Fabricate, test X-LAT heat pipes Assemble, test X-LAT Thermal Plates Assemble, test mid-plate Radiators Quantity Flt/Spare Responsible Work Organization Performed 1/0 5/1 12 / 1 1/0 SLAC LM-ATC SLAC Sub LM-HPPC SLAC 9/1 2/1 1/0 LM-ATC LM LM-HPPC LM-ATC Sub Fabricate, inspect Radiator parts Fabricate, test Radiator VC heat pipes 12 / 1 LM-ATC LM-HPPC Assemble, inspect Radiators 2/0 LM-ATC LM-HPPC LM-ATC SLAC LM-ATC Sub LM-ATC Test Radiators Thermal Control System Fabricate TCS hardware Thermal-balance test TCS system 1/1 1/0 Mechanical Systems Legend LM-ATC LMHPPC SLAC Sub Lockheed-Martin Advanced Technology Center, Palo Alto CA Lockheed-Martin Heat Pipe Product Center, Sunnyvale CA Stanford Linear Accelerator Center, Menlo Park CA Subcontractor to be determined Document: LAT-PR-01967 Section 13 Mechanical Systems 7

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Problem Areas • CAL-GRID GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Problem Areas • CAL-GRID Interface • Electronics-Box to X-LAT Interface Document: LAT-PR-01967 Section 13 Mechanical Systems 8

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface Status • The design shown at PDR for the Calorimeter to Grid interface was a bolted joint with 54 - #8 bolts & 16 - #6 bolts • Two pins provide alignment – one slip fit and one slot • Further analysis has shown that this design is inadequate – Inadequate margin between the required friction coefficient to prevent slipping and the achievable coefficient • Alternate designs are being pursued by analysis and test – Create a pinned joint using structural epoxy around a bolt – A combination of pins and bolts – An alternate path for shear loads leaving the original arrangement of bolts for clamping in Z – Unique Cal plates around the periphery • The Instrument Office and the Project Office are reviewing the shear load requirements • This interface remains an open issue Document: LAT-PR-01967 Section 13 Mechanical Systems 9

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL-Grid I/F Closure Plan • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL-Grid I/F Closure Plan • Re-evaluated approach for deriving the shear load requirement – Factor of ~2 reduction predicted 5/6 • New shear loads from CLA – First look 5/16 – Verified 5/30 • EM test of CAL Shear plate concept – First look 5/21 (load capability) – Full up test 6/7 • Detail design complete 6/27 – Coordinated with CAL, I & T and ELEC (cable trays) • 1 x 4 EM testing complete 7/31 Document: LAT-PR-01967 Section 13 Mechanical Systems 10

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to Electronics-Box Thermal Joint GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to Electronics-Box Thermal Joint Design Problem Status • At PDR & d. PDR the baseline design was a bolted and thermally bonded joint between bottom of each E-Box and the X-LAT plate. There were flexures between the top of the E-box stack and the CAL plates. X-LAT Plate – Concern that E-boxes were not serviceable • Large bonded area to de-mate. • Re-verification issues after re-integrating. GRID • At Peer Review, trade study presented for design that – Carried thermal load of E-Boxes into X-LAT heat pipes – Accommodate tolerance buildup from E-Box and Grid Box components – Repeatable interface (make & break) – Minimize schedule & verification impacts resulting from XLAT plate removal for Electronics box access Document: LAT-PR-01967 Section 13 Mechanical Systems 11

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to Electronics-Box Thermal Joint GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to Electronics-Box Thermal Joint Design Problem Resolution • Design changed to rigidly mount E-Box stack to CAL plate and create a thermally compliant thermal joint between the E-box & X-LAT plate • Trade study results indicate that graphite “felt” material optimally meets requirements and has the following characteristics: – Highly conductive graphite fibers – Mechanically compliant – Meets out-gassing requirements – Allows TEM/TPS to be mated to CAL through out its Acceptance testing • However, this approach has limited Flight heritage and must be qualified for our application – GSFC Wide Field Planetary Camera 3 has qualified an application Document: LAT-PR-01967 Section 13 Mechanical Systems 12

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Vel-Therm Design Closure Plan GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Vel-Therm Design Closure Plan • Design trades 5/30 – Contact pressure distribution (# bolts, preload) – Particle containment – E-box – X-LAT mechanical connection details • Vel-therm EM tests – Coupon tests (load-deflection & conductance-psi) 5/30 – Full scale tests 7/15 – Life tests – thermal and/or mechanical cycling 12/12 • Flight designs 8/29 – Finalize interface – Revise/release affected hardware – Assembly plans & procedures – Coordinate with I & T Document: LAT-PR-01967 Section 13 Mechanical Systems 13

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Peer Review Significant Findings • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Peer Review Significant Findings • Is the design maturity, qualification and verification planning near CDR level? – With the exception of the electronics to X-LAT interface, Yes, but still missing an appropriate level of verification with the engineering models and final dynamics analysis. • Has the Subsystem identified open design issues and established appropriate resolution plans to ensure closure? – Yes, the issues have been identified but issues may still develop during engineering model testing and final analysis. • Is the Subsystem near readiness for manufacturing? – Many element of the subsystem are ready for manufacture (e. g. radiator), however other items need to wait until analysis and successful engineering model completion. • Has the Subsystem identified open manufacturing issues and established appropriate resolution plans? – Yes. Specific concerns are captured in the RFAs. • Are there other issues that should be addressed? – Mechanical assembly of the LAT will be a complex process that will require development of detailed processes and procedures. – The mechanical team has just recently staffed up. Re-plan of work that has been delayed needs to be completed and may delay design finalization. Document: LAT-PR-01967 Section 13 Mechanical Systems 14

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s and Overall Status GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s and Overall Status • 19 of 46 Mechanical/Thermal RFA’s owned by Mechanical Systems (M. Campell & S. Morrison) – 0 closed – 19 submitted Document: LAT-PR-01967 Section 13 Mechanical Systems 15

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s and Overall Status GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s and Overall Status Top 5 RFA Summary • #12 a) Address the intermetallic layer issue at the friction joint of the bimetallic joint for VCHP’s; b) request information on manufacturing processes; c) are CCHP end caps friction welded? – Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. – Temperatures are controlled during subsequent fusion welding processes to remain below approximately 200 o. F. Fusion welding is automated, allowing minimum heat input to the parts. Inert gas flow provides sufficient cooling to limit temperatures during and after the welding process. This ensures that material integrity is not compromised due to overheating. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls. • #29 Establish a realistic schedule for drawing release include spans for design engineering, check, stress, configuration management, etc – Schedule has been revised to include these items Document: LAT-PR-01967 Section 13 Mechanical Systems 16

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s (Cont) Top 5 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s (Cont) Top 5 RFA Summary (Cont) • #34 Verify that proposed Vel-therm X-LAT to electronics thermal joint design thermal performance does not degrade over time (aging issue), after multiple installation/de-installations, and during the course of the mechanical vibration – A qualification program will be developed for this interface to address these issues. Looking for guidance from GSFC WFC 3 program. • #42 a) What is the detailed schedule for the Vel-Therm EM Test program. Document: LAT-PR-01967 Section 13 Mechanical Systems 17

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s (Cont) Top 5 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Major RFA’s (Cont) Top 5 RFA Summary (Cont) • #42 b) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconventional. – 3 Back-ups are under consideration; #1 will be developed – “Thick” RTV bond line between E-box and X-LAT plate with a 0. 0005 inch thick Teflon film between one of the interfaces to allow disassembly. – A thermal strap that is laminated with the Grafoil (high conductance graphite). – Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the E-boxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in-phase. Document: LAT-PR-01967 Section 13 Mechanical Systems 18

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems’ Status Summary • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems’ Status Summary • • • Final Design Established With Known Closure Plans For Design Trades – X- LAT Plate To Electronics Interface - ECD: 7/15/03 • Qual tests ECD: 11/15/03 – CAL-Grid Interface – ECD: 7/15/03 – EM Model Tests Complete - ECD: 9/03 – Grid Box Assy Drawings – ECD: 8/03 • 0/26 Drawings Released, 23/26 Drawings Draft – Radiator & X-LAT Drawings – ECD: 6/15/03 • 0/39 LM Drawings Released, 39/39 LM Drawings Draft Internal & External Interfaces Established – 87 TBX’s with closure planned – ECD: 6/1/03 Performance Analyses Will Show Compliance Including Sufficient Design Margin – Analyses ECD: 5/30/03 – Exception: CAL-Grid interface currently has negative margins Qualification & Verification Plans – X-LAT test plan ECD: 5/30/03 – GBA Static Load test case definition ECD: 8/03 – TCS Thermal Balance test definition ECD: 8/03 Subsystem Risk Areas Identified And Mitigation Plans Established Cost & Schedule Manageable – +$364 K Cost and -$544 K Schedule Variance with recovery plans in work – 60 Days Schedule Float to Flight Delivery Need Dates Document: LAT-PR-01967 Section 13 Mechanical Systems 19

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Key Requirements Section 13. 2 Section 13 Mechanical Systems 20

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (1 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (1 of 2) Sect Requirement 8 Configuration 8. 1. Mass The total mass of Mechanical Systems <345 kg Design Margin Comply Method Req. Source 8. 3. 329. 3 15. 7 Y I LAT-TD-00125 -1 >1. 89 m 1. 895 Y I IRD 3. 2. 2. 3 Stay-Clear Volume and Dimensions Radiator positioned according to IRD Appendix A When on, Radiator VCHP heater power < 35 W Y D 158 W 62 W Y D When off, peak survival heater power < 560 W 8. 6. 22 W When off, orbit-average survival heater power <220 W @ 27 V min 8. 5. 13 W 533 27 W Y D 55. 5 Hz 11% Y T IRD 3. 2. 2. 8. 1. 2 Y T, A IRD 3. 2. 2. 8. 1. 2 Stiffness Fixed-base first-mode > 50 Hz Provisions for Integration and Test During Obs T-Vac, TCS capable of full functionality “lying on its side” Document: LAT-PR-01967 Ok TD-00125 -1(Derived) IRD 3. 2. 4. 1. 7. 6 (Derived) Section 13 Mechanical Systems 21

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (2 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (2 of 2) Sect Requirement 10 Design Margin Comply Method Req. Source Structural Load Environment 10. 1. Structural Loads Capable of exposure to launch loads Ok Y* IRD 3. 2. 2. 8. 2 A Y T, A LAT-TD-00225 -5 Y T, A IRD 3. 2. 3. 4. 5 Y T, A MSS 3. 3. 2. 3 (Derived) Capable of maintaining thermal control during exposure to IR, Albedo, Solar fluxes 11. 1. Y Provide thermal control with LAT pointed 2 pi/24/7/365 73. 4 W/Rad 0 W/Rad during any normal LAT mode 11 Capable of withstanding static loads in thrust and lateral Ok simultaneously Thermal Environment and Heat Loads T, A Y T, A IRD 3. 2. 3. 5 (Derived) Process and Interface Heat Loads Maximum process power indefinite dissipation 615 W LAT+ 35 W Rad 0. 6 C hot case Capable of normal operation when loaded by 75 W/Rad From SC solar arrays 11. 3. IRD 3. 2. 2. 8. 2 Environment Heat Loading and Orbital Parameters * Will comply for CAL-Grid interface Document: LAT-PR-01967 Section 13 Mechanical Systems 22

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 Design Grid Box Assembly Section 13. 3 Document: LAT-PR-01967 Section 13 Mechanical Systems Design 23

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Drawing Tree Document: LAT-PR-01967 Section GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Drawing Tree Document: LAT-PR-01967 Section 13 Mechanical Systems 24

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Design +Z GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Design +Z CAL-Grid Interface Mid-Plate X-LAT Plate Assy +Z Radiator Mount Bracket Heat Pipe Patch Panel EMI Shields S/C Mount Interface Document: LAT-PR-01967 Section 13 Mechanical Systems 25

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Structure +Z S/C mount GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Structure +Z S/C mount Helicoils for CAL bolts +Z Top Flange Heat Pipes Purge grooves Integral Wing Document: LAT-PR-01967 Section 13 Mechanical Systems 26

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Design Drivers • Provides GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Design Drivers • Provides structural backbone for all LAT Subsystems • Provides electrical ground for all LAT Subsystems • Provides thermal path to Radiators for all LAT Subsystems except Electronics boxes (carried by X-LAT plates) – Embedded Heat Pipes in top flange of Grid to move heat out – Downspout Heat pipes tie Grid to Radiators • Thermostatically controlled heaters on Grid corners are part of LAT thermal control system Construction • Machined from 10. 25” thick 6061 AL plate • Heat treated to T 6 after rough machining • Grid surface is alodine, class 3. Electrically conductive and good surface for adhesive bonding thermal components, harness supports, Tracker cables, MLI supports, EMI tape etc • Integral purge grooves allow for N 2 purging of the CAL’s during ground operations Document: LAT-PR-01967 Section 13 Mechanical Systems 27

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Spacecraft Interface Stiffener (Wing) Design GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Spacecraft Interface Stiffener (Wing) Design Drivers • Primary function is to spread the point load inputs from the Spacecraft & locally stiffen the Grid against the lateral loads. – Distortions in this area drive the CAL-Grid interface design • Defines Spacecraft interface to LAT Construction • Integral part of Grid (was separate part) • S/C Interface is a raised pad with 2 – 12. 7 mm dia inserts & 1 – 14. 3 mm dia pin hole at each location – Installed with Spectrum Astro provided fixture +Z Document: LAT-PR-01967 Section 13 Mechanical Systems 28

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Mount Bracket Design Drivers GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Mount Bracket Design Drivers • Supports & locates Radiators & their Heat Pipes • Supports & locates X-Lat Plates & their Heat Pipes • Provides access to ACD mounting bolts • Supports & locates alignment optics • Provisions for mounting Heater Control Box or Heater Control Connector Bracket for Thermal Control System • Corner lugs for MGSE attachment (sized to carry entire Observatory mass with 2 lugs if required) Construction • 6061 -T 6 Al machining, alodine • Bolts/pinned to 3 orthogonal surfaces of Grid corner Document: LAT-PR-01967 Section 13 Mechanical Systems 29

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 EMI Shield Design Drivers • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 EMI Shield Design Drivers • Encloses LAT Electronics boxes (EMI tight) • Consists of 4 Radiator Mount Brackets, 4 Heat Pipe Patch Panels, 4 X-side Shields and 4 center Shields • Mechanically supports 3 way heat pipe joint – Downspout, XLAT and Radiator HP’s • Supports X-LAT plates • Provides mounting for Connecter Patch Plates from Electronics +Z Construction • 6061 -T 6 AL machining, alodine • Pieces bolted to Grid & each other Document: LAT-PR-01967 Section 13 Mechanical Systems 30

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Calorimeter to Grid Interface • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Calorimeter to Grid Interface • Interleaved CAL baseplate tabs are bolted and pinned to –Z surface of Grid • CAL baseplates close-out the Grid structure which increases natural frequency of LAT • Bolted interface applies clamping force for Z axis loads and provides good thermal contact • Features to carry shear loads are under investigation • 2 pins per CAL locate it on the Grid bay and are used as datum for hole pattern in Grid and other features such as Tracker cable cut-outs in Grid walls Document: LAT-PR-01967 Section 13 Mechanical Systems 31

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Plate to E-Box Thermal GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Plate to E-Box Thermal Joint • Thermal joint design drivers – Carry thermal load of stack of E-Boxes into X-LAT Heat Pipes – Accommodate tolerance stack up E-Box and Grid Box parts – Be repeatable & reliable – Minimize schedule & verification impacts due to removal of X-LAT plates for access to Electronics • Graphite felt material selected – Highly conductive graphite fibers – Mechanically compliant – Meets out-gassing requirement – Vel-Therm & Vel-met are brand names Document: LAT-PR-01967 Section 13 Mechanical Systems 32

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Electronics Stack Cross-Section • 4 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Electronics Stack Cross-Section • 4 cm wide graphite felt strip placed around perimeter of each box optimizes conduction vs contact pressure required Midplate to X-LAT Thermal Joint, 2 PLCS, 60 #6 Fasteners each side Vel-Therm X-LAT Plate Midplate Bolting X-LAT Plate to EMI Shields, 60 #8 Fasteners per Plate X-LAT Plate EMI Shields GRID Note: View along Y-axis Document: LAT-PR-01967 Section 13 Mechanical Systems 33

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Stress Analysis Topics • Cal-Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Stress Analysis Topics • Cal-Grid interface load recovery • Grid Stress analysis • Radiator Mount Bracket analysis Document: LAT-PR-01967 Section 13 Mechanical Systems 34

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Interface Load Recovery • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Interface Load Recovery • CAL-Grid joint – 1152 connections (72 per CAL module) – CAL plate stiffens LAT by closing out bottom side of Grid • Load recovery – Interface loads are backed out from the FEA model by resolving nodal forces at the interface into shear (X & Y) loads at the pin locations and Z loads at bolt locations – EM pinned joint tests validated manufacturability but Capacity req’d at insufficient load capacity highest loaded tab Demonstrated Best We with 1. 25 factor Load Capacity Can Do* Grid Wall 750 lb Cal Plate Tab 750 925 lb 1300 1460 -2010 lb 1460 -2010 * Includes 0. 160 close fit pin in grid wall and CAL plate tab and material properties of 2618 A for CAL plate Document: LAT-PR-01967 Section 13 Mechanical Systems 35

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Stress Analysis • Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Stress Analysis • Grid stress analysis indicates positive margins of safety for all regions – Nominal maximum Von Mises stress is order of magnitude below yield for material – Large corner radii in the actual design, not included in the model, limit stress risers – Top flange in model has a weighted-average cross section which is no more than twice the minimum cross sectional area • Highest stresses occur in transition regions around SC mount • Grid material properties – Material: 6061 -T 6 aluminum (6061 -T 651, stress-relieved, then heat-treated during fabrication) – Sy = 240 MPa (35 ksi) – Su = 290 MPa (42 ksi) • Factors of safety (per NASA-STD-5001) – Metallic structures • Yield: FSy = 1. 25 • Ultimate: FSu = 1. 4 Document: LAT-PR-01967 Section 13 Mechanical Systems 36

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Mount Bracket Analysis Design GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Mount Bracket Analysis Design Loads and critical load cases • Loads defined in Environmental Spec – FS=1. 25 (PFQ) used for launch loads – FS=1. 40 used for lift case • Assume Observatory lift load is carried in 2 of 4 fittings • Critical Load Cases Study results CASE X [N] Y [N] Z [N] +X/-Z 994 0 -1670 -X/-Z -994 0 -1670 +Y/-Z 0 333 -1670 -Y/-Z 0 -333 -1670 LIFT 0 0 32400 – – Lift case induces the highest stresses Margins of safety are good for all design cases Calculated stiffness is high, which is conservative for loads determination The radiator attachment bracket meets or exceeds all design requirements Document: LAT-PR-01967 Section 13 Mechanical Systems 37

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Summary • Summary – Integrated GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Summary • Summary – Integrated LAT structural analysis results of the staticequivalent load cases indicate that LAT deflections and stresses are within required limits – Grid stress analysis shows that the Grid design is not highly-stressed, but driven more by the natural frequency requirement Document: LAT-PR-01967 Section 13 Mechanical Systems 38

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 Verification Program Grid Box Assembly Section 13. 4 Document: LAT-PR-01967 Section 13 Mechanical Systems 39

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Verification Topics GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Verification Topics • EM Tests • Qualification & Flight Test Overview • Mechanical Systems Verification Test Flow • Mechanical Systems Verification Matrix Document: LAT-PR-01967 Section 13 Mechanical Systems 40

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 EM Test Plans Overview • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 EM Test Plans Overview • EM test plans developed for: – CAL-Grid Joint Testing (complete) • Friction characterization • Bolt-Helicoil pair characterization • Bolted Pull tab coupons • Pinned Pull tab coupons – 1 x 4 Grid – Grid heat pipe bonding process qualification – Thermal Joint candidates (complete) • “Wet” adhesive or gasket • Low contact pressure • No contact pressure – X-LAT heat pipe characterization (complete) Document: LAT-PR-01967 Section 13 Mechanical Systems 41

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 1 x 4 Grid Planned GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 1 x 4 Grid Planned Tests • Purpose: Validate finite element model used for LAT predictions to date – Model created from full up model – Full scale CAL-Grid interactions • Test Set up: 1 x 4 Grid design is flight like – Partial bays with partial CAL plates provide interleaving CAL tabs – Load hydraulically applied 6 places – Reacted out at corners – Deflections measured along length – Record load vs deflection 1 x 4 Grid Document: LAT-PR-01967 Section 13 Mechanical Systems 42

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Planned Process Tests 1 x GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Planned Process Tests 1 x 4 Grid unit fabrication • Objectives – Demonstrate Grid manufacturability – Demonstrate purge gas system – Provide unit to I&T group for I&T EM testing • Risks mitigated or retired – Fabrication errors, process problems (cost & schedule impact) Document: LAT-PR-01967 Section 13 Mechanical Systems 43

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 3 -Way Heatpipe Thermal Joint GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 3 -Way Heatpipe Thermal Joint Conductance Test 3 -Way heatpipe thermal joint conductance test • Objectives – Determine thermal joint that can meet conductance and ease of assembly requirement – Develop design-specific empirical conductance values for actual bolted joint configuration • Results – Conductance values agree with published data – Nusil CV 2946 is difficult to work with – Single 3 way joint assembled • Risks mitigated – Validates thermal model based on empirical thermal conduction values Document: LAT-PR-01967 Section 13 Mechanical Systems 44

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Thermal Joint Further Work • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Thermal Joint Further Work • Demonstrate Radiator installation process – 6 wet RTV joints in vertical orientation & restricted access – Complete within pot life limits (bonded & torqued) – Verify bond line integrity (uniform thickness & % voids) • Demonstrate Radiator removal process – Separate 6 joints with restricted access – No damage or distortions of heat pipes – Verify material can be cleaned up & surface prepared again for another bond Document: LAT-PR-01967 Section 13 Mechanical Systems 45

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to E-box Thermal Joint GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT to E-box Thermal Joint Candidates Tested • “Wet” adhesive or gasket joints – Thermally conductive silicone adhesive, Nusil CV 2946 – Sil. Pad, VO Gap Pad • Low contact pressure joints – Off-the-shelf EMI gasket products, i. e. Be. Cu spring fingers, electrically conductive elastomers – Graphite velvet pad (Vel-Therm from ESLI or Vel-Met) • No contact pressure joints – High conductivity materials mechanically fastened at both ends – Formed Copper sheets (30 mils) – Pyrolytic Graphite Sheet (4 mils thick stock) • Conductance vs. various gaps and/or pressures examined Document: LAT-PR-01967 Section 13 Mechanical Systems 46

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Thermal Joints EM Evaluation Summary GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Thermal Joints EM Evaluation Summary • • Vel-Therm material is best candidate among those evaluated to meet all design drivers – Thermal data indicate material can meet required conductance – Material is bonded to one surface prior to installing X-LAT plate, minimal fasteners required – Allow sliding contact for lateral flexibility –. 125” thick material can fill gap of. 05 to. 10” Quantify contact pressure versus brush compression Document: LAT-PR-01967 Section 13 Mechanical Systems 47

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Planned Work • Additional Vel-Therm GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Planned Work • Additional Vel-Therm coupon tests – Conductance in high vacuum vs. contact pressure • Additional thermal joint configuration tests – Mock up box stackup configuration with heaters on sidewalls to simulate electronics heat source – Flight like installation procedure for Vel-Therm to identify process problems and errors – Perform Random Vibe and Thermal Vacuum tests to retire risks associated with contamination, thermal conductance at min & max fiber compression levels Document: LAT-PR-01967 Section 13 Mechanical Systems 48

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT EM Heat Pipe Characterization GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT EM Heat Pipe Characterization Tests • Objectives – Verify thermal performance of EM X-LAT heat pipe in simulated on-orbit thermal cases • Key Result – Alternate Heat Pipe condensers at each end were cycled on and off without Heat Pipe dry out. – Heat pipe was not sensitive to small tilt angles at thermal loads applied • Risks mitigated – Demonstrate adequate design margins – Assure that heat pipe performs as predicted Document: LAT-PR-01967 Section 13 Mechanical Systems 49

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems Verification Test Flow GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems Verification Test Flow Grid Structure -Proof Load -Mass Properties & C. G. -Dimension Check Radiator Mount Bracket X-LAT Plates -Static Load Test -Mass Properties & C. G. -Dimension Check -Thermal Vacuum Test Grid Box Base Assembly Disassemble Grid Box Base Assembly Grid Box Assembly -Static Load -Thermal Cycle -Mass Properties & C. G. -Dimension Check -Alignment -Functional -Static Load Grid Assembly LAT Integration X-LAT Plates Mid-Plate X-LAT Plates -Static Load Test -Mass Properties & C. G. -Dimension Check Radiator -Sine Sweep -Acoustic -Mass Properties & C. G. -Dimension Check -Interface Verification -EMI/EMC -Functional Document: LAT-PR-01967 Assemble Radiator pair test configuration Radiators LAT Level Verification Tests -Thermal Balance -Mass Properties & C. G. -Dimension Check Section 13 Mechanical Systems 50

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Subsystem Verification Matrix LEGEND GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Subsystem Verification Matrix LEGEND Assembly Level S – Subsystem A- Assembly C – Component Unit Type PF – Proto Flight F – Flight S – Spare Document: LAT-PR-01967 Q – Qual E – Engineering Model V – Verification Model Verification Method T – Test TQ – Test, Qualification Level A –Analysis TA – Test, Acceptance Level M – Measurement P – Proof I – Inspection Section 13 Mechanical Systems 51

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 4 x 4 Grid Structure GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 4 x 4 Grid Structure Verification Mass Properties & C. G. Verified Document: LAT-PR-01967 Dimension Check Verified Proof Test of Inserts Section 13 Mechanical Systems 52

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Verification Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Verification Grid Box Assembly Dimension Check Grid Box Assembly Functional Test Document: LAT-PR-01967 Grid Box Assembly Mass Properties/C. G. Grid Box Assembly Alignment Check Grid Box Assembly Functional Test Grid Box Assembly Thermal Cycle Grid Box Assembly Functional Test Grid Box Assembly Static Load Test Section 13 Mechanical Systems 53

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Static Load Test • • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Static Load Test • • Test Objectives – Primary Objective: Verify static strength and stability of the Grid Box Assembly under worst case Delta II-H vehicle loads of 1. 25 times limit loads • Achieve maximum stresses in grid box assembly • Load subsystem interfaces to qualification design loads – Secondary Objective: Verify the design analysis process by comparing measured strains and deflections to predictions from the finite element analysis model Test Success Criteria – Successful test completion is when all load cases have been performed and it is verified that no yielding, buckling, de-bonding, or fractures have been observed. • A visual inspection is to be performed after each load case to check the critical joints and bonded interfaces • A review of all pertinent data during test including deflections and strains to verify linearity Document: LAT-PR-01967 Section 13 Mechanical Systems 54

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Static Load Test GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Static Load Test Configuration • • The test configuration consists of all primary structure grid box components as described below The test article will be grounded at the SC Mount Brackets with correct degrees of freedom Grid - Flight Radiator Mount Brackets - 4 X Flight EMI Skirts - Flight Calorimeter Plates -16 X Flight-like Down spout HPs - 12 X - Flight Spacecraft Mount Brackets - 4 X - Flight XLAT Plate - Flight Document: LAT-PR-01967 Section 13 Mechanical Systems 55

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 Fabrication Process Grid Box Assembly Section 13. 5 Document: LAT-PR-01967 Section 13 Mechanical Systems 56

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Overview Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Overview Grid Assy Grid Box Base Assy Grid Box Assy Ready for Test Radiator Mount Bracket EMI Skirt Details Heat Pipe Patch Panels X-LAT Plates Heat Pipes Purge Groove Cover CAL Plates (Temporary) Legend Accepted Hardware Test activity Assembly activity Document: LAT-PR-01967 Grid Box Assembly Configuration Section 13 Mechanical Systems 57

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Machining Assembly • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Machining Assembly • “Grid Box Machining” is a temporary assembly for machining: – EMI shields coplanar for X-LAT plate mounting – Each pair of Radiator Mounting Brackets coplanar – Control relative positions of Radiator & X-LAT locating pins to Grid datum’s so 3 sets of heat pipes will mate properly • • • Install the EMI Skirt components on Grid Machine bottom edges of the EMI Skirt components co-planer Machine X-LAT locating pin holes and fastener holes in the EMI Skirt components Machine mounting features & locating pins holes in Radiator Mounting Brackets Install locating pins and Helicoils Mark parts for specific location on Grid X-LAT Pins Radiator Pins Document: LAT-PR-01967 Section 13 Mechanical Systems 58

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 Design, Analysis & Fabrication Radiator and X-LAT Assemblies Section 13. 6 Brenda Costanzo Lockheed Martin Systems Engineer brenda. [email protected] com Program Manager: Susan Morrison E-Mail: susan. [email protected] com Document: LAT-PR-01967 Section 13 Mechanical Systems 59

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Responsibility Overview • Lockheed Martin GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Responsibility Overview • Lockheed Martin hardware responsibilities: – Design, fabrication, and test of the Top Flange Heat Pipes – Design, fabrication, and test of the Downspout Heat Pipes – Design, fabrication, and test of the Radiator Assembly – Design, fabrication, and test of the X-LAT Assembly • Additional Lockheed Martin responsibilities: – Thermal analysis for the LAT instrument (covered separately) – LAT thermal systems engineering consultation Document: LAT-PR-01967 Section 13 Mechanical Systems 60

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Requirements Basis • Radiator requirements GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Requirements Basis • Radiator requirements based on: – Radiator Level IV Design Specification, • LAT-SS-00394 -1 -D 6, draft • Dated 5 Mar 2003 – LAT Mechanical Systems Interface Definition Drawing, Radiator. LAT Interface • LAT-DS-01221, draft • Dated 25 Feb 2003 • X-LAT requirements based on: – X-LAT Plate Performance Specification • LAT-TD-01240 -D 3, draft • Dated 19 March 2003 – X-LAT Plate Assy Source Control Drawing • LAT-DS-01247, draft • Dated 7 March 2003 – Mid-Plate Assy Source Control Drawing • LAT-DS-01257, draft • Dated 7 March 2003 Document: LAT-PR-01967 Section 13 Mechanical Systems 61

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (HPs) • Top GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (HPs) • Top Flange Heat Pipes (TFHP) – Five constant conductance pipes – Mounted in the +Z surface of the grid – Isothermalize grid – Move energy to DSHP’s • Down Spout Heat Pipes (DSHP) – Twelve (6 +Y, 6 –Y) constant conductance pipes – Mounted to the +Y and –Y sides of the grid – Move energy from the TFHP’s to the radiator heat pipes Document: LAT-PR-01967 Section 13 Mechanical Systems 62

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Sizing • All GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Sizing • All worst case pipe requirements derived from detailed thermal model hot case with the following assumptions and results Document: LAT-PR-01967 Section 13 Mechanical Systems 63

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Structural Analysis • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Structural Analysis • • • Top Flange and Downspout Heat Pipes external loads insignificant relative to internal loads due to mounting configuration X-LAT Heat Pipe analysis will be performed once LAT loads are received VC Heat Pipe preliminary analysis covering reservoir and transition complete with the following assumptions and results: – MEOP of 377 PSI (140ºF)**(requirements changed to 490 PSI) – MPP of 882 PSI (210 ºF) – Acceleration loads of 35 G’s replace external flight loads Location Loading Condition Yield Ultimate FOS M. S. Reservoir – Inertia Weld MEOP 1. 5 3. 5 4. 0 1. 0 Reservoir – Inertia Weld MPP 1. 1 1. 6 1. 25 1. 7 Transition Tube – Orbital Weld MEOP 1. 5 6. 7 4. 0 6. 2 Transition Tube – Orbital Weld MPP 1. 1 3. 8 1. 25 9. 5 Transition Tube – Inertia Weld MEOP 1. 5 7. 0 4. 0 6. 5 Transition Tube – Inertia Weld MPP 1. 1 3. 7 1. 25 9. 3 Transition Tube – Inertia Weld MEOP + Acceleration 1. 6 3. 6 2. 0 8. 2 Document: LAT-PR-01967 Section 13 Mechanical Systems 64

 • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (Radiators) • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (Radiators) Two radiator panels – Honeycomb core with Aluminum facesheets – Six Variable Conductance Heat Pipes (VCHPs) embedded in each panel – FOSR radiating surface – MLI on non-radiating surfaces – Maintains LAT temperatures – Structural interfaces at the LAT grid and S/C – Thermal interface between Radiator VCHPs, X-LAT CCHPs, and Heat Pipe downspout CCHPs Interface (6 pl/Rad) Document: LAT-PR-01967 +Z +Y +X Radiator Panels Section 13 Mechanical Systems 65

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Panel, Exploded Outer Facesheet GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Panel, Exploded Outer Facesheet VCHPs Doublers Honeycomb Core 1. 56 m Inner Facesheet Z X Y Reservoir Support Bar 1. 82 m Document: LAT-PR-01967 Section 13 Mechanical Systems 66

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Structural Performance Summary • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Structural Performance Summary • • • Preliminary analysis indicates the revised Acoustic spectrum produce smaller loads than the assumed dynamic load factor of 30 g Positive stress margins obtained for sandwich panel, bolts, inserts and heat pipes Frequency requirement, >50 Hz, satisfied. Design frequency 61. 6 Hz Radiator First Five Natural Frequencies Document: LAT-PR-01967 Normal Mode 1, f 1 = 61. 6 Hz, 1 st YZ Bending Mode Section 13 Mechanical Systems 67

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results Face Sheet Margins • • Facesheet stress analysis indicates positive margins of safety for all highstress regions Facesheet material properties – Material: 6061 -T 6 aluminum (Top: 0. 060” thk, Btm: 0. 030” thk) – Ftu = 296 MPa (43 ksi) – Fty = 255 MPa (37 ksi) Facesheet Stresses and Margins of Safety Document: LAT-PR-01967 MSy = Fty/(1. 25 si) – 1 MSu = Ftu/(1. 4 si) – 1 Section 13 Mechanical Systems 68

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results Core Shear Margins • Core shear stress analysis indicates positive margins of safety for all highstress regions – Basic Core Material: 5000 series aluminum • • Fsu 12 = 35 k. Pa (5 psi) Fsu 13 = 1379 k. Pa (200 psi) Ribbon Dir; Fsu 23 = 758 k. Pa (110 psi) – Hi_Den Core Material: 5000 series aluminum, density is ~2*basic core density • • Fsu 12 = 69 k. Pa (10 psi) Fsu 13 = 3. 62 MPa (525 psi) Ribbon Dir; Fsu 23 = 2. 10 MPa (305 psi) LD = Basic core material HD = High density core material Bi-axial quadratic failure criterion: MSu = 1/SQRT((Fs. tyz/(Ks*Fsu 13))2 + (Fs. txz/(Ks*Fsu 23))2) -1 Where: Ks=0. 9 Core Stresses and Margins of Safety Document: LAT-PR-01967 Section 13 Mechanical Systems 69

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results Heat Pipe Margins • • Heat pipe stress analysis indicates positive margins of safety for all stressed regions Heat pipe material properties – Material: 6063 -T 6 aluminum – Ftu = 241 MPa (35 ksi); Fty = 214 MPa (31 ksi) Heat Pipe Stresses and Margins of Safety (includes 170 psi int. pressure) Document: LAT-PR-01967 MSy = Fty/(1. 25 si) – 1 MSu = Ftu/(1. 4 si) – 1 Section 13 Mechanical Systems 70

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Stress Analysis Detailed Results Bolt/Insert Margins • • Bolt and insert analysis indicates positive margins of safety Bolt material properties – Material: CRSS A-286 stainless steel – Ftu = 1. 103 GPa (160 ksi); Fty = 0. 827 GPa (120 ksi) – Fsu = 0. 655 GPa (95 ksi) • Insert ultimate strengths (Estimated from existing tests. GLAST specific tests to be performed) – 5/16”-24 UNF insert • • Pull-out = 6. 47 k. N (1454 lb) Shear = 7. 16 k. N (1610 lb) – 10 -32 UNF insert • • Pull-out = 3. 56 k. N (800 lb) Shear = 4. 79 k. N (1077 lb) * Note: Factor of safety on Ultimate = 1. 4, Yield = 1. 25, Fittng factor = 1. 15 Bolt and Insert Stresses and Margins of Safety Document: LAT-PR-01967 MSy = Fty/(1. 25 si) – 1 MSu = Ftu/(1. 4 si) – 1 Section 13 Mechanical Systems 71

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Thermal Performance Summary • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Thermal Performance Summary • • LAT input powers – Qmax = 602 W (615 W analyzed) – Qmin = 475 W (495 W analyzed) Requirement: Tmax RIT <15 °C Qavg Reservoir < 48 W – Predictions • Tmax RIT = 10 °C • T max. RIT = 14 °C, 1 HP failed • Qavg Reservoir = 0 W Requirement: Tmin RIT >-10 °C Qavg Reservoir < 48 W – Predictions • Tmin RIT = -5 °C • Qavg Reservoir = 13 W Requirement: Tmin RIT >-20 °C, Survival Qavg Reservoir < 58 W * – Predictions • Tmin RIT = -20 °C • Qavg Reservoir = 42 W Cold RIT Temperatures * Value pending Document: LAT-PR-01967 Section 13 Mechanical Systems 72

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Requirement Compliance (1 of GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Requirement Compliance (1 of 2) • Key requirements not formally defined or compliance is in question * Specification Change Pending Document: LAT-PR-01967 Section 13 Mechanical Systems 73

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Requirement Compliance (2 of GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Requirement Compliance (2 of 2) • Key requirements not formally defined or compliance is in question * Specification Change Pending Document: LAT-PR-01967 Section 13 Mechanical Systems 74

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Compliance Mitigation Plans (1 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Compliance Mitigation Plans (1 of 2) • Mass – Primary mitigation step is for SLAC to increase the radiator mass allotment if necessary – If mass allotment is exceeded, can reduce thickness of honeycomb core • Impact to structural design margin • CG in Z-direction – Expected mitigation is to change requirement to CG located no less than 720 mm from datum – If requirement change is not incorporated, can add weights to –Z edge of radiator panel • Impact to structural design margin • Impact to mass • Dynamic envelope – Expected mitigation is to change requirement of dynamic envelope to +2 mm beyond static envelope. – If change is not incorporated, can reduce thickness of honeycomb core • Impact to structural design margin Document: LAT-PR-01967 Section 13 Mechanical Systems 75

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Compliance Mitigation Plans (2 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Compliance Mitigation Plans (2 of 2) • Static envelope – Currently working with SLAC to increase localized static envelope – If envelope can not be increased, can do all or some of the following: • Reduce thickness of honeycomb core – Impact to structural design margin • Remove MLI from back side of VCHP reservoirs – Impact to heater power – Impact to VCHP performance • Remove option of repinching VCHPs (1 pinch per fill tube) – Increase cost risk • Power allocations – Expected mitigation is to impose requirements that bound current design case (see compliance tables). – If power can not be allocated, can do all or some of the following • Decrease radiator size – Impact to hot case LAT temperatures Document: LAT-PR-01967 Section 13 Mechanical Systems 76

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (1 of 2) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (1 of 2) Obtain Facesheet Material Shear Obtain Remaining Flight Materials Bond Pipes To OB Facesheet N/C Machine Log Flight Materials Inspect Thermal Bond Visual Process Samples To Lab CMM Inspect Geometry Inspect Doublers Document: LAT-PR-01967 Bond OB Doublers AC Cure Inspect Purchasing Clean, Etch & Prime Inspection/Test Manufacturing Inspect Verify Flight Materials Fit Check Core Inspect Holes w/ Pins Verify Cure Profile Assemble Panel and Bond Verify Cure Profile Prep and Install Inserts & Spools Bond Top Edge Closure Inspect Inserts & Spools Machine Transfer Datums Bond IB Doublers RT Cure A Section 13 Mechanical Systems 77

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (2 of 2) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (2 of 2) A Bond Reservoir Supports Install Reservoir Bushings Fit Check Reservoir Bushings Inspect Reservoir Supports Inspect Bushings Apply Blanket Velcro Machine Bushings Apply Edge Closure Tape Apply Thermal Blanket Inspect Bushings Structural Testing Final Cosmetic Damage Map Thermal Testing Notes 1) All panel moves require: inspection documentation of panel for damage; packaging for transport; and flight approved move procedures. 2) No outside storage. 3) Qualified flight transportation personnel and equipment. Document: LAT-PR-01967 Section 13 Mechanical Systems 78

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (X-LAT Assy) • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Hardware Overview (X-LAT Assy) • X-LAT Assembly – Two X-LAT plate assemblies • 3. 2 mm (1/8”) solid Aluminum plate • Three Constant Conductance Heat Pipes (CCHPs) per plate – One mid-plate • 4. 8 mm (3/16”) solid Aluminum plate – Moves heat from electronics to radiators – Load shares between radiator panels Document: LAT-PR-01967 Heat Pipe Interface (6 pl/Side) +Z X-LAT Assembly Section 13 Mechanical Systems 79

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Design • • • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Design • • • CCHPs are bonded and riveted to X-LAT plates are interchangeable Material is 0. 125” 6061 Aluminum X-LAT Plate Assy (2 x) CCHP (3 pl) Mid- Plate (1 x) Push-Pull Bolt Interface Hole (12 pl, TBR) Push-Pull Bolt Interface Hole (24 pl, TBR) X-LAT Plate Interface to Mid-Plate Interface To X-LAT Plate (both sides) Radiator Bracket Alignment Pin Hole Document: LAT-PR-01967 Section 13 Mechanical Systems 80

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Structural Performance Summary • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Structural Performance Summary • • Model was simply supported at the edges, and constrained in the Z direction only at each of the spacer locations Frequency Requirement, > 50 Hz – Analysis: First mode = 97. 7 hz Loads – Highest load on plate is random vibration – Calculate 3 s random vibration load factor in g using Miles’ equation => 3*sqrt((p/2)*PSD*Q*f)), where: • PSD at first resonant frequency is 0. 08 g**2/Hz (source – LAT-TD 01240) • Q = 50 (1% damping) • F = 97. 7 Hz Load cases run – 74. 4 g acceleration normal to plate – 74. 4 g g lateral in plane of plate Document: LAT-PR-01967 Load Case Stress (KSI) Yield Safety Margin Ultimate Safety Margin 1: 74. 4 g Normal Load 11. 2 +1. 92 +1. 68 2: 74. 4 g In. Plane Load . 32 +101. +93. Stress for 74. 4 g normal load Section 13 Mechanical Systems 81

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Thermal Performance Summary 17. GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Thermal Performance Summary 17. 3 °C EPU PDU 20. 3 °C 20. 4 °C Comb 22. 6 °C 20. 3 °C 24. 2 °C GASU 22. 3 °C 21. 3 °C Comb • 17. 3 °C Comb • Qmax = 359. 9 W Qmin = 286. 2 W Requirement: Tmax <35 °C – Predictions • Tmax = 24. 2 °C Requirement: Tmin >-10 °C Qavg Reservoir < 48 W – Predictions • Tmin RIT = -5 °C Note: Not identified are the 16 TEM/TPS stacks Comb • • • 19. 4 °C EPU SIU 20. 1 °C Y X Document: LAT-PR-01967 Section 13 Mechanical Systems 82

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Requirement Compliance • The GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Requirement Compliance • The following table addresses key requirements that are not yet defined Document: LAT-PR-01967 Section 13 Mechanical Systems 83

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Compliance Mitigation Plans • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Compliance Mitigation Plans • Must define/finalize requirements and determine whethere’s a non-compliance. If there is, the following plan will be activated: – Temperature Limits and Electronics Power Values • Increase conduction from the X-LAT to the warm electronic(s) • If there is still a problem, increase thickness of the X-LAT panel(s) – Impact on structural and mass margins – Envelope • Increase dynamic envelope to accommodate dynamic motion • If dynamic envelope can not be changed, increase panel thicknesses – Impact on thermal, structural, and mass margins – Loads • Adjust panel thicknesses – Impact on thermal, structural, and mass margins Document: LAT-PR-01967 Section 13 Mechanical Systems 84

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12 -16, 2003 Verification Radiator and X-LAT Assemblies Section 13. 7 Brenda Costanzo Lockheed Martin Systems Engineer brenda. [email protected] com Program Manager: Susan Morrison E-Mail: susan. [email protected] com Document: LAT-PR-01967 Section 13 Mechanical Systems 85

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator and X-LAT Verification • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator and X-LAT Verification • Test plan is document GLS 0002 -03 • All testing will have procedures written prior to commencement • Inspection occurs throughout the testing at points specified in the procedure • Flash reports will be written within 3 working days of test completion • Full reports will be written within 30 days of test completion or by pre -ship review, whichever is earlier Radiator In-Process Tests Radiator Acceptance Tests VCHPs Only Heat Pipe In-Process Tests Heat Pipe Acceptance Tests X-LAT CCHPs Only X-LAT In-Process Tests Document: LAT-PR-01967 Integrated Radiator & XLAT Assy Thermal Test X-LAT Assy Acceptance Tests Delivery In. Place to SLAC TCS Thermal Test (TBR) Deliver to SLAC Section 13 Mechanical Systems 86

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Structural and EMI Verification • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Structural and EMI Verification • Each radiator panel tested individually Radiator Vibration Testing Pre. Vibration IR Signature Low Level Sine Survey Acoustic Vibration Sine Vibration Limit Load Test Post. Vibration IR Signature Radiator EMI Testing (TBR) Mass Properties Radiated Emissions Conducted Emissions Radiated Susceptibility Conducted Susceptibility X-LAT/Radiator Assy Thermal Testing • Tested at the X-LAT Assembly level X-LAT Vibration Testing Low Level Sine Survey Static Load Test Random Vibration (TBR) Document: LAT-PR-01967 Sine Vibration (TBR) Acoustic Vibration (TBR) Low Level Sine Survey Mass Properties Section 13 Mechanical Systems Deliver to SLAC 87

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Assy Thermal GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Assy Thermal Testing (1 of 2) • • Hardware configuration – X-LAT Assy – Radiator Assy – Heater plate to introduce heat into the system – Lab electronics to control VCHPs Hardware orientation – +X side up – Level within 0. 10” NO SCALE Flight Radiators (2) X-LAT Assy Cold Wall +X MLI Blanket +Y Document: LAT-PR-01967 Gravity is into page Section 13 Mechanical Systems 88

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Assy Thermal GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator & X-LAT Assy Thermal Testing (2 of 2) Pump Down Chamber Pre-Cycling Functional Test Thermal Cycle 1 Bakeout / Hot Survival Hot Temperature Turn-On Cold Survival Cold Temperature Turn-On Thermal Cycle 3 Thermal Cycle 2 Hot Balance Point Cold Balance Point Thermal Cycle 4 Hot Balance Point Cold Portion of Thermal Cycle Post-Cycling Functional Test Delivery In. Place to SLAC Document: LAT-PR-01967 IR Signature TCS Thermal Testing (TBR) Section 13 Mechanical Systems 89

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 TCS Thermal Testing • Hardware GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 TCS Thermal Testing • Hardware Configuration – Radiator Assy – X-LAT Assy – Downspout heat pipes (TBR) – LAT mass simulator • Test Objective – Verify VCHP reservoir heater operational algorithm • Test Flow Pump Down Chamber Pre-Cycling Functional Test Hot Balance Point Cold Balance Point Document: LAT-PR-01967 Bakeout / Hot Survival Cold Temperature Turn-Off Hot Balance Point Hot Temperature Turn-On Cold Survival Post-Cycling Functional Test Cold Temperature Turn-On Repressurize Chamber Section 13 Mechanical Systems 90

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Further Work • Design – GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Further Work • Design – Review finalized control documents to assess impacts to requirements compliance, cost, and schedule – Resolve any non-compliances • Fabrication – Begin writing shop orders – Complete fixture design and manufacture • Test – Complete development tests • Heat Pipe bend • Insert pull tests (radiator) • Push-pull bolt lateral slip testing (X-LAT) – Negotiate contract terms to allow joint thermal testing of radiator and X-LAT assemblies – Determine need for TCS thermal testing Document: LAT-PR-01967 Section 13 Mechanical Systems 91

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Cost and Schedule Section 13. 8 Section 13 Mechanical Systems 92

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CCB Actions Affecting 4. 1. GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CCB Actions Affecting 4. 1. 8 Change Request # Description Status LAT-XR-01149 -01 Lockheed Martin Contract Rebaseline Approved, $56 K LAT-XR-01159 -01 Procurements Move Approved, $0 K from FY 04 to FY 03 LAT-XR-01585 -01 Transfer to 4. 1. 1. 5 Instrument Design Engineering Approved, -$1. 4 M LAT-XR-01621 -01 Mass Allocation Increase Approved, 22 kg LAT-XR-01752 -02 SLAC/HEPL Labor Escalation Rates Approved -$39 K Document: LAT-PR-01967 Section 13 Mechanical Systems 93

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 4. 1. 8 Work Flow GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 4. 1. 8 Work Flow Summary Document: LAT-PR-01967 Section 13 Mechanical Systems 94

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Deliverable Milestones Forecast Baseline GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Key Deliverable Milestones Forecast Baseline Document: LAT-PR-01967 Product Available Date Integration Need Date Section 13 Mechanical Systems 95

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Critical Path Document: LAT-PR-01967 Section GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Critical Path Document: LAT-PR-01967 Section 13 Mechanical Systems 96

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Budget, Cost, Performance Document: LAT-PR-01967 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Budget, Cost, Performance Document: LAT-PR-01967 Section 13 Mechanical Systems 97

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cost/Schedule Status • Status as GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cost/Schedule Status • Status as of March 31, 2003: Item In k$ Budget at Complete 10, 373 Budgeted Cost for Work Scheduled (a) 4, 643 (a) Budgeted Cost for Work Performed (b) 4, 099 (b) Actual Cost for Work Performed 3, 735 Cost Variance 364 8. 9% of (b) Schedule Variance -544 -11. 7% of (a) Document: LAT-PR-01967 Section 13 Mechanical Systems 98

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Procurements • Long-Lead Procurements – GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Procurements • Long-Lead Procurements – Aluminum Billets (placed) – Heat pipe extrusions (LM - placed) – Solid State thermostats (LM) • Major Upcoming Procurements Near-Term (< 4 months) – Lockheed Martin Phase 2 – Grid Assembly – Flight Hardware for Thermal Control System • Major Upcoming Procurements Long-Term (>4 months) • Minor Upcoming Procurements – GSE – Grid Assembly Fixtures, Test Equipment – Thermal-vac Test Fixtures Document: LAT-PR-01967 Section 13 Mechanical Systems 99

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Risk and Summary Section 13. 9 Section 13 Mechanical Systems 100

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Mech GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Mech 0008 Risk Rank Risk Description Risk Mitigation Ability to ramp up & maintain personnel required to execute Mechanical Systems plan High Document: LAT-PR-01967 Update manpower plan. Locate or request additional funds. Hire additional help. Negotiate transition of technicians from MECH to I&T that is acceptable to both with IPO buy in. Section 13 Mechanical Systems 101

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk Rank Risk Description Risk Mitigation • X-LAT plate to Electronics box thermal joint does not perform as designed • 1) Clarity interface responsibilities and requirements -complete • 2) Detail interface options -complete • 3) Complete interface analysis – prelim. Complete (Wang) Mech 0001 • 4) Prototype interface techniques (Lam ) High • 5) Complete detail box thermal analysis (Haller) • 6) Select Design approach (Campell) • 7) Complete integrated analysis (Wang) • 8) Complete EM Test (Lam) • Same as Mech 0001 • Repeatable X-LAT Thermal Joint Mech 0006 performance Moderate • X-LAT plates are removed to service electronics boxes • X-LAT plates could be removed after LAT or Observatory thermal testing Document: LAT-PR-01967 Section 13 Mechanical Systems 102

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk Rank Risk Description Risk Mitigation • Delays in Lockheed Martin document finalization may impact cost & schedule. Mech 0009 Mech 0010 • All future changes controlled by formal revision through Contracts Moderate • Release Radiator & X-LAT level IV specifications & IDD's by 5/12/03 Incorrect hardware may be built due to Release controlling documents. changes and proposed changes being given Changes to these documents to be to various LM personnel sent through Contracts (May 03 and beyond) Document: LAT-PR-01967 Section 13 Mechanical Systems 103

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk Rank Risk Description Risk Mitigation • Repeatable Radiator Thermal Joint Performance Mech 0007 Moderate • 1) Same as Mech 0002 • “Wet” joint is disassembled & reassemble after LAT thermal balance test • 6 joints per radiator must be made within pot life of thermal adhesive Mech 0002 Low Document: LAT-PR-01967 • Radiator VCHP to Downspout and X-LAT heat pipes thermal joint fails during thermal vac test • 1) Prototype verification test (ECDJuly 03) • 2) Develop process control requirements (ECD-Aug 03) Section 13 Mechanical Systems 104

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Risk Summary ID # Risk Description Risk Mitigation • Availability of Grid and ACD-BEA for match drilling at mutually acceptable timeframes Mech 0005 Risk Rank • Establish multiple windows of opportunity to do the operation and or additional tooling Low • 1) Develop schedule window workarounds (ECD – June 03) • 2) Evaluate creating drill template to remove schedule dependency (ECDJune 03) Document: LAT-PR-01967 Section 13 Mechanical Systems 105

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Appendix A Requirements Section 13 Mechanical Systems 106

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Requirements Flow GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Requirements Flow down And Document Status • Key Mechanical Systems Requirements (Level 3) • Heat Pipe Performance Requirements • Radiator Design Requirements • Main X-LAT Design Requirements • Driving X-LAT Thermal Requirements Document: LAT-PR-01967 Section 13 Mechanical Systems 107

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Requirements Flow-Down and Documentation Status GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Requirements Flow-Down and Documentation Status LAT Perf Spec LAT-SP-00010 -1 31 Aug 2000 LAT Stay-Clear Drawing LAT-DS-00040 -5 LAT Envir. Spec LAT-SS-00778 -1 10 Feb 2003 Mech Systems Subsystem Spec LAT-SS-00115 -2 Subsystem ICD’s Subsystem IDD’s LAT Thermal Design Param’s LAT-TD-00224 -3 LAT Dissipated Power Summary LAT-TD-00225 -3 LAT Instrument Layout Dwg LAT-DS-00038 -3 Document: LAT-PR-01967 X-LAT Design Spec LAT-SS-00124 -3 X-LAT Plate SCD LAT-DS-01247 -1 Radiator Design Spec LAT-SS-00394 -1 Mid-Plate SCD LAT-DS-01257 -1 Grid Box Design Spec LAT-SS-00775 -1 Thermal Control Sys. Perf. Spec LAT-SS-00715 -1 Radiator IDD LAT-DS-01221 -1 Top Flange Heat Pipe SCD LAT-DS-01393 -1 LH/RH Down Spout Heat Pipe SCD LAT-DS-01392 -1 LAT-DS-01393 -1 Section 13 Mechanical Systems 108

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Performance Requirements Based GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Heat Pipe Performance Requirements Based on: Results of Overall LAT Thermal Math Model Verification Methods A: Analysis T: Test Margin is determined by: EP/Req Must be > 1. 3 Document: LAT-PR-01967 Section 13 Mechanical Systems 109

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Mechanical) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Mechanical) Document: LAT-PR-01967 Section 13 Mechanical Systems 110

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Structural) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Structural) Document: LAT-PR-01967 Section 13 Mechanical Systems 111

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Thermal) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Thermal) Document: LAT-PR-01967 Section 13 Mechanical Systems 112

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Mechanical) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Mechanical) Document: LAT-PR-01967 Section 13 Mechanical Systems 113

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (X-LAT) Document: GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Driving Design Requirements (X-LAT) Document: LAT-PR-01967 Section 13 Mechanical Systems 114

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Appendix B Fabrication Process Grid Box Assembly Section 13 Mechanical Systems 115

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Fabrication plans GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Fabrication plans • Assembly plans • MGSE • Performance and Safety Assurance plans • Further Work Document: LAT-PR-01967 Section 13 Mechanical Systems 116

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Parts & Materials Plan GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Parts & Materials Plan • Material requirements flow down from the Mission Assurance Requirements 433 -MAR-0001 and the Mechanical Parts Plan LAT-SS 00107 -01. • LAT Material selection of low outgassing and flight heritage • Outgassing specs: TML < 1% CVCM < 0. 1% • Important Procedures and Guidelines for Material selection • Fastener Integrity Requirements (541 -PG-8072. 1. 2) • Metallic Materials for Stress Corrosion Cracking Resistance in Sodium Chloride Environment (MSFC-STD-3029) • Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials for Outgassing (ASTM-E-595) Document: LAT-PR-01967 Section 13 Mechanical Systems 117

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 LM M & P Plan GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 LM M & P Plan & EEE Parts • LM M & P Plan submitted to SLAC (GLS 00018 -2, dated 1 Feb 2003) • LM EEE Parts – Heaters: Minco Kapton Foil Heaters per GSFC S-311 -P-079 – Thermistors: YSI Thermistors per GSFC S-311 -P-18 – RTDs: Rosemount PRT per GSFC S-311 – Solid State Thermostats: Micropac 52372”O” • Submitted to SLAC for approval Nov 2002 Document: LAT-PR-01967 Section 13 Mechanical Systems 118

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Overview Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly Overview Grid Assy Grid Box Base Assy Grid Box Assy Ready for Test Radiator Mount Bracket Spacecraft Interface (Wing) EMI Skirt Details Heat Pipe Patch Panels X-LAT Plates Heat Pipes Purge Groove Cover Legend Accepted Hardware CAL Plates (Temporary) Grid Box Assembly Configuration Test activity Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Systems 119

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Assembly The Grid Assembly GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Assembly The Grid Assembly consists of; • 4 x 4 Grid • Radiator Mounting Brackets - 2 as shown and 2 opposite. Radiator Mounting Bracket Document: LAT-PR-01967 Grid Assembly Section 13 Mechanical Systems 120

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Base Assembly The GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Base Assembly The Grid Box Base Assembly is the next level assembly, and is the configuration delivered to I&T. It consists of: • Grid Assembly • Heat Pipe Patch Panels, 2 as shown and 2 opposite • Heat Pipes – 5 Top Flange Heat Pipes (TFHP) – 12 Downspout Heat Pipes (DSHP) • 2 Purge groove covers • Flight heaters, thermostats & thermistors on Grid Once this assembly is put together, it is not intended to be taken apart. Grid Box Base Assembly Heat Pipe Patch Panel Document: LAT-PR-01967 Section 13 Mechanical Systems 121

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly The Grid GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Assembly The Grid Box Assembly is the Mechanical Systems’ top assembly test configuration. It consists of: • Grid Box Base Assembly • Remaining EMI skirt parts – 4 Center EMI Shields – X-EMI Shields, 2 as shown and 2 opposite Grid Box Assembly • 2 X-LAT plates with heat pipes • X-LAT Mid-plate • 16 Temporary Calorimeter plates. Center EMI Shield Document: LAT-PR-01967 X-EMI Shield Section 13 Mechanical Systems 122

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Fabrication Grid Procure aluminum GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Fabrication Grid Procure aluminum NDT plate (x-ray, UT, other) Rough machine Grid Stress-relieve heat treat Finish machine Grid Remove, mach test samples Test samples Clean Grid Inspect Grid Inserts Procure inserts, mount h’ware Repair as required Alodine Install inserts Proof inserts Ready for Grid Box Machining SLAC Buy-off Final Inspection Legend Fabrication activity Inspection/test Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Systems 123

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Machining EMI Skirt GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Grid Box Machining EMI Skirt Grid Procure aluminum Grid Machine Radiator Brkts Machine Patch Panels Clean EMI Skirt Components Inserts Procure inserts, mount h’ware Machine Center EMI Shields Machine X-EMI Shields Install inserts in EMI Skirt Parts Inspect Repair as required Install Radiator Brkts, Patch Panels, Center EMI Shields, & X-EMI Shields on Grid Repair as required Inspect Clean Assy Drill Pin and Bolt Holes in EMI Skirt Parts & Radiator Brkts Machine Radiator mounting surface features in Radiator Brkts Machine EMI Skirt Co-planer Legend Install inserts in EMI Skirt Parts Deliver To SLAC Fabrication activity Inspection/test Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Systems 124

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (1 of 2) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (1 of 2) Obtain Facesheet Material Shear Obtain Remaining Flight Materials Bond Pipes To OB Facesheet N/C Machine Log Flight Materials Inspect Thermal Bond Visual Process Samples To Lab CMM Inspect Geometry Inspect Doublers Document: LAT-PR-01967 Bond OB Doublers AC Cure Inspect Purchasing Clean, Etch & Prime Inspection/Test Manufacturing Inspect Verify Flight Materials Fit Check Core Inspect Holes w/ Pins Verify Cure Profile Assemble Panel and Bond Verify Cure Profile Prep and Install Inserts & Spools Bond Top Edge Closure Inspect Inserts & Spools Machine Transfer Datums Bond IB Doublers RT Cure A Section 13 Mechanical Systems 125

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (2 of 2) GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Radiator Fabrication (2 of 2) A Bond Reservoir Supports Install Reservoir Bushings Fit Check Reservoir Bushings Inspect Reservoir Supports Inspect Bushings Apply Blanket Velcro Machine Bushings Apply Edge Closure Tape Apply Thermal Blanket Inspect Bushings Structural Testing Final Cosmetic Damage Map Thermal Testing Notes 1) All panel moves require: inspection documentation of panel for damage; packaging for transport; and flight approved move procedures. 2) No outside storage. 3) Qualified flight transportation personnel and equipment. Document: LAT-PR-01967 Section 13 Mechanical Systems 126

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems MGSE Document: LAT-PR-01967 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Mechanical Systems MGSE Document: LAT-PR-01967 Section 13 Mechanical Systems 127

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Performance Assurance System • Mechanical GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Performance Assurance System • Mechanical Systems will comply with the following: – LAT Performance Assurance Implementation Plan (PAIP), LAT-MD-00039 – LAT Quality Manual, LAT-MD-00091 – Configuration Management Plan, LAT-MD-00068 – Instrument Performance Verification Plan, LAT-MD-00408 – Calibration Program, LAT-MD-00470 – System Safety Program Plan (SSPP), LAT-MD-00078 • Additionally, above requirements have been flowed down to Suppliers and Subcontractors. Document: LAT-PR-01967 Section 13 Mechanical Systems 128

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Appendix C Peer Review RFAs Section 13 Mechanical Systems 129

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 1 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 1 10 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan • Verify that Grid Finite Element Model reflects the flange cutaways for the downspout heat pipes. Assess stress concentrations at these reduced flange section areas. • The Grid has been re-designed to incorporate the spacecraft interface wing as an integral feature of the grid. The lower flange has been extended to become the wing. This removes the discontinuities that were in the old design. Analysis for this new design has just begun. ECD: 5/12/03 Complete design and structural Analysis is in work. ECD: 5/12/03 analysis of S/C to LAT interface. Present margins of safety for LAT side of interface hardware Section 13 Mechanical Systems 130

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 12 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 12 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan 1) Address the intermetallic layer issue at the friction joint of the bimetallic joint for VCHPs. 2) What does LMC do from a manufacturing process point of view to preclude this layer from forming during the integration welding process, including temperature control during processing? 3) Do LMC CCHPs use a friction weld to cap off CCHPs? Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. Temperature control is not directly applicable to the friction welding process, however other process controls on weld energy are used in conjunction with weld process certification to carefully regulate weld quality. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls. Section 13 Mechanical Systems 131

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 27 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 27 Status Open Document: LAT-PR-01967 RFA Description Please identify and capture development of process specifications for adhesive applications, painting (if any) etc RFA Response/Closure Plan LAT processes are being developed by Jerry Clinton. MECH specific processes will be developed and written prior to flight hardware assembly. Here is a list of processes MECH will use in the assembly of the Grid Box Assembly. Section 13 Mechanical Systems 132

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 28 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 28 29 32 Status RFA Description RFA Response/Closure Plan Open • Review heat pipe installation • Protective covers will be used for to see whether any protection as long as practical. They have covers can be used during been added to the MECH MGSE list. ground handling and mechanical operations to prevent any accidental damage. Both the grid and radiator design appears to be vulnerable to damage. Open Establish a realistic schedule for drawing release with “buyin” from all parties required for process completion, i. e. design engineering, check, stress, configuration management, etc The drawing release plan is being revised to add time for feedback from the interested parties. ECD: 5/12/03 Verify ESD requirements are correctly flowed down to LMC from LAT Working with ELEC to define applicable ESD requirements to flow down to LM. ECD: 5/12/03 Open Document: LAT-PR-01967 Section 13 Mechanical Systems 133

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 33 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 33 Status RFA Description RFA Response/Closure Plan Open • The plan is to put the antifreeze heaters on the front/FOSR side of the radiator and have the FOSR cover the heater. Look at the impact of putting the heater on the backside. At the temperatures the anti-freeze heaters will operate, the panel gradients should be small (small qdot = small delta T). • A study will be performed to evaluate the anti-freeze heater design. Specifically, the study will address the plausibility of placing the anti-freeze heaters on the nonradiating side of the radiators. It is anticipated that this study will be complete by CDR. 5/12/03 Document: LAT-PR-01967 Section 13 Mechanical Systems 134

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 34 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 34 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan Verify that proposed Vel-therm X-LAT to electronics thermal joint design thermal performance does not degrade over time (aging issue), after multiple installation/deinstallations, and during the course of the mechanical vibration these program. A qualification program will be developed for this interface to address these issues. However, the Wide Field Planetary Camera-3 (WFC 3) is a GSFC program that used this material. The instrument is waiting to fly. Therefore, it must have qualified and acceptance tested. If GSFC could provide the details of what testing was done and the test results, it would streamline our testing. Perhaps there is Qual by Similarity possibilities here that would reduce costs as well. Section 13 Mechanical Systems 135

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 36 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 36 37 38 39 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan • Define allowable load transfer into LAT (or radiator strut stiffness) at connection of radiator to S/C. An effective stiffness of the spacecraft support strut of at least 200, 000 lb/in (strut plus Spacecraft) was used in the Radiator analysis. This should be flowed down to Spectrum Astro in the S/C working group or as a requirement from GSFC to Spectrum. Limit load tests should qualify the design (1. 25 x flight limit loads) The Level IV spec will be revised. ECD: 5/12/03 Update yield F. S. to 1. 25 (currently @1. 1). Verify that this requirement has been flowed down to all other subcontractors. The Level IV spec will be revised. ECD: 5/12/03 Provide more detailed summary of stress margins of safety for the LAT instrument. Stress analyses are in work. ECD: 5/12/03 Section 13 Mechanical Systems 136

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 40 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 40 41 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan • Review high conductance graphic interface material available from a company named “UCAR” (formerly part of Union Carbide). They have high conductance graphite material gaskets greater than 10 mil in thickness. They have space experience. • Received 0. 020” & 0. 025” thick samples from Vendor. While the material (Grafoil) has excellent compressive properties, it has very low tensile strength (~1, 000 psi). Therefore, when bending the material, it breaks. We are investigating laminated versions of the product to see if they are feasible for this application. Verify that the flight data certification packages that accompany hardware delivered by Lockheed to SLAC are consistent with NASA Quality Assurance Requirements. NASA has not imposed any requirements for data package requirements on LAT (per Darren Marsh). However, Lockheed’s data package will be consistent with the LAT’s internal requirements (Mechanical to I & T) and their own standards for their Government Customers. Section 13 Mechanical Systems 137

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID Stat # GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID Stat # us 42 Open RFA Description RFA Response/Clo sure Plan • 1) What is the detailed schedule for completion of the EM Test program for the X-LAT Thermal/Mech Design, will it be complete by CDR? • 1)EM test program schedule (below) • 2) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconvention Document: LAT-PR-01967 Section 13 Mechanical Systems 138

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # Open GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # Open RFA Description RFA Response/Closure Plan • 1) What is the detailed schedule for completion of the EM Test program for the X-LAT Thermal/Mech Design, will it be complete by CDR? 42 Cont. Status 2) Back-up designs (in descending order) “Thick” RTV bond line between E-box and X-LAT plate with a 0. 0005 inch thick Teflon film between one of the interfaces to allow disassembly. The existing push-pull bolts would still be required for Z axis restraint (parts are not bonded together). A thermal strap that is laminated with the Grafoil (high conductance graphite, see RFA # 40). Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the Eboxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in phase. • 2) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconventional Document: LAT-PR-01967 Section 13 Mechanical Systems 139

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 43 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 43 Status Open Document: LAT-PR-01967 RFA Description RFA Response/Closure Plan Consider including GRID & DSHPs in the “Complete TCS” TB test. Schedule chart 1. 2 -4 shows cycling of grid assy by ¾ with “complete TCS test” in 6/04. Chart on page 3. 1 -10 conveys this config for the TB test Definition of the test & hardware requirements is in work. Examining schedule options including combining thermal vacuum acceptance testing of the radiators & X-LAT plates with this TCS TB test. The Grid delivery to I&T need date currently precludes its availability for this test, but will be part of configuration trade study (configuration vs. cost, schedule & risks mitigated). ECD: 7/13/03 Section 13 Mechanical Systems 140

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # RFA GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # RFA Description RFA Response/Closure Plan • GSFC (Brad Parker/Materials Board) provide recommendation to SLAC/LM team regarding the use of bimetal element used in heatpipes 45 Status Same as #12. Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. Temperature control is not directly applicable to the friction welding process, however other process controls on weld energy are used in conjunction with weld process certification to carefully regulate weld quality. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls. Open Document: LAT-PR-01967 Section 13 Mechanical Systems 141

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 46 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 RFA Response ID # 46 Status RFA Description RFA Response/Closure Plan Will add a “Qualification” (one time-one part) test to the Lockheed Martin Radiator specification and/or SOW. ECD 5/12/03 Open Consider defining a “control performance” test for each VCHP that verifies ability to entirely block off the condensor, as well as ability to run full open under spec boundary conditions Document: LAT-PR-01967 Section 13 Mechanical Systems 142

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD-3 Review May 12 -16, 2003 Back-up charts Section 13 Mechanical Systems Risk & Summary 143

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL-Grid I/F Closure Plan • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL-Grid I/F Closure Plan • New shear loads from CLA – First look 5/16 – Verified 5/30 • EM test of CAL Shear plate concept – First look 5/21 (load capability) – Full up test 6/7 • Detail design complete 6/27 – Coordinated with CAL, I & T and ELEC (cable trays) • 1 x 4 EM testing complete 7/31 Document: LAT-PR-01967 Section 13 Mechanical Systems 144

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface Status • Loads analysis of interface used to determine required friction coefficients to prevent slipping at cal tab locations. Required friction compared to that determined to be achievable in test. – The upper limit of friction achievable with special surface treatments is needed to prevent slipping with the baseline design. – Devices to increase clamping force at perimeter of grid still require friction coefficients at a small number of locations which exceed the friction achievable with normal surface finishes. – Friction alone has not been shown to provide high confidence that local (not bulk) slipping will not occur. Analysis to determine load redistribution and potential for subsequent slipping after initial slipping is not readily accomplished. Document: LAT-PR-01967 Section 13 Mechanical Systems 145

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Cal Plate to Grid Interface Status (cont) • Converting select fasteners in clearance holes to pins via epoxy fill of the clearance gap studied as a means to provide confidence against local slipping. – Epoxy installation technique and strength demonstrated on test coupons. – Upon application of shear load, male threads of fastener mating with female threads in grid rib cause excessive dead band. Mated threads do not effectively carry shear loads. • Other techniques for strengthening the interface under study – Replace select fasteners with traditional shear pins in tight holes. Requires template for drilling grid and cal plates. Most dead band found in threads will be eliminated but strength of grid walls and / or cal tabs may be inadequate. – Carry shear loads directly from cal plates to grid wings by adding shear plates that attach to cal plates at existing GSE fastener location. Existing fasteners from cal plates to grid provide axial restraint forces. Document: LAT-PR-01967 Section 13 Mechanical Systems 146

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Shear Plate Concept 5/16 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Shear Plate Concept 5/16 bolts pressed or tight slip fit into CAL plates and Grid perimeter. Cal plate location is at current location of tapped GSE hole. Grid perimeter Document: LAT-PR-01967 Section 13 Mechanical Systems 147

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Shear Plate Concept PRO’s GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 CAL Shear Plate Concept PRO’s CON’s • Allows shear loads to be carried through M 8 ( 5/16 inch) fasteners • Mold release and a design feature are required on bolts with epoxy fill in order to accomplish shear plate removal. Some additional confidence testing in epoxy is required. • Cal plate tabs and grid walls are not in the primary shear load path • No dependence on friction • Minor changes to cal plates and wings. • Epoxy shear holes will be in shear plates so that no holes need to be drilled in M 8 fasteners. Document: LAT-PR-01967 • Clearance envelope above the pressed in bolts in the cal plate needs to be checked. • Removal of a cal plate requires removal of shear plates on adjacent cal plates Section 13 Mechanical Systems 148

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Vel-Therm Design Closure Plan GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Vel-Therm Design Closure Plan • Design trades 5/30 – Contact pressure distribution (# bolts, preload) – Particle containment – E-box – X-LAT mechanical connection details • Vel-therm EM tests – Coupon tests 5/30 – Full scale tests 7/18 – Life tests – thermal and/or mechanical cycling 12/12 • Flight designs 8/29 – Finalize interface – Revise/release affected hardware – Assembly plans & procedures – Coordinate with I & T Document: LAT-PR-01967 Section 13 Mechanical Systems 149

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Back-up Thermal Design Plans GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Back-up Thermal Design Plans • Develop concepts 1. “Thick” RTV bond line between E-box and X-LAT plate with a 0. 0005 inch thick Teflon film between one of the interfaces to allow disassembly. The existing push-pull bolts would still be required for Z axis restraint (parts are not bonded together). Complete 2. A thermal strap that is laminated with the Grafoil (high conductance graphite, see RFA # 40). ECD 5/30 3. Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the E-boxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in phase. ECD ? Need Analysis • Coupon test #1 6/13 Document: LAT-PR-01967 Section 13 Mechanical Systems 150

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Plate Thermal Loads +Y GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 X-LAT Plate Thermal Loads +Y EPU 39 W 15 W 15 W 15 W 21 W GASU SIU 21 W PDU 21 W 37 W EPU 39 W Heat Source within box 15 W Note: View from X-LAT Plate to E-boxes Power shown include 15 W from TEM/TPS boxes Document: LAT-PR-01967 15 W 42 W -X Power numbers Source: LAT-TD-00225 -4 (draft) EPU 39 W X-LAT Heatpipe 6 Required Section 13 Mechanical Systems 151

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Particulate Containment Options • Perimeter GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Particulate Containment Options • Perimeter (foam) gasket • Tape over the Vel-therm • Vel-therm sandwich between 2 Aluminum plates with Kapton tape close outs • Shower cap bonded to X-LAT & slip over E-box Document: LAT-PR-01967 Section 13 Mechanical Systems 152

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Conductance vs Pressure Document: LAT-PR-01967 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Conductance vs Pressure Document: LAT-PR-01967 Section 13 Mechanical Systems 153

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Vel-Therm Pressure vs. Deflection Document: GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Vel-Therm Pressure vs. Deflection Document: LAT-PR-01967 Section 13 Mechanical Systems 154

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Drawing Release Plan Document: LAT-PR-01967 GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Drawing Release Plan Document: LAT-PR-01967 Section 13 Mechanical Systems 155

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Summary of Margins of Safety GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Summary of Margins of Safety 26 14 15 27 25 12 11 16 13 22 23 24 Tension Failure Document: LAT-PR-01967 Bearing Failure Tear Out Failure Section 13 Mechanical Systems 156

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Mechanical design GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Topics Agenda • Mechanical design changes since ∆PDR • Impacts on Subsystem design • Studies since Delta PDR Document: LAT-PR-01967 Section 13 Mechanical Systems 157

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR • X-LAT to E-Box thermal joint – WAS: Rigid bonded joint with flexures at CAL-TEM interface – IS: Rigid interface at CAL-TEM with compliant joint at XLAT plate and a thermal velvet material (Vel-therm) used to fill gap between bottom box & X-LAT • X-LAT plate • WAS: honeycomb panel; IS: . 125” plate • CAL-Grid bolts: • Use #8’s everywhere except at TRK cables pass-thru’s to increase clamping force on CAL plate Document: LAT-PR-01967 Section 13 Mechanical Systems 158

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR • Refined S/C interface stiffener (wing) to reduce grid distortions • S/C attach method – WAS: onto –Z surface of Grid – IS: tang that protrudes down from wing • S/C stayclear & center EMI shield design modified to accommodate above Document: LAT-PR-01967 Section 13 Mechanical Systems 159

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR • E-box harnesses – WAS: bulkhead connectors in EMI skirt – IS: 8 Connector patch panels into EMI skirts that E-box harness mount directly to • Added 2 TCS external box & 2 brackets – mounting accommodated on Radiator Mount Brackets • Added vents to EMI Electronics enclosure Document: LAT-PR-01967 Section 13 Mechanical Systems 160

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Design Changes Since Delta PDR • Radiator Heat Pipes – WAS: U shaped bend to Grid – IS: S shaped bend to Grid • Radiator panel has top stepped for integration access • Radiator – SC interfaces have been finalized – SA Boom cutout size & location, strut locations • Radiator reservoir size – WAS 300 cc; IS: 75 cc • Radiator VCHP extrusion – WAS 1. 75” wide; IS: 2. 0” wide • LM will design, fabricate and test X-LAT plates Document: LAT-PR-01967 Section 13 Mechanical Systems 161

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Impact of Changes on Subsystem GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Impact of Changes on Subsystem Designs • • • LAT – No impact TKR – No impact CAL – Baseplate design has been modified for #8 fasteners ACD – No impact Electronics – Improved reliability by reducing bulkhead connection – External TCS boxes have been accommodated Conclusion: Changes consistent with PDR to CDR design maturity. Design changes have been incorporated within the Mechanical Subsystem Document: LAT-PR-01967 Section 13 Mechanical Systems 162

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • X-LAT to Electronics Thermal Joint Design • Optimize joint design to accommodate – Maximum thermal conductance – Repeatable and verifiable thermal joint – Ease of integration & removal to service E-boxes – Compliance in X-Y plane required either at E-box to CAL or E-box to X-LAT – Tolerance stack up of E-boxes, EMI skirts & CAL plates • RTV, thermal gaskets, spring fingers, thermal straps and Vel. Therm traded • Compliant joint at E-box to X-LAT interface with Vel-Therm material in between selected. Document: LAT-PR-01967 Section 13 Mechanical Systems 163

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • CAL-Grid interface shear load capability – No bulk movement of CAL with 70 Fasteners & μ=. 01 – Isolated concern as small local motions of Grid wall underneath grid tabs – Optimize wing design to reduce loads (FEM) – Examined friction of various surface treatments – Examined Tungsten Carbide flame spray as a way to guarantee high coefficient of friction at interface – Maximized clamping force available from fasteners – Examined backing bars on top of CAL tabs to create “double shear” joint – Examined perimeter clamping bars that increase preload on all CAL tabs around the perimeter of the Grid – Developed maps from FEM showing required coefficient of friction at each bolt location for a given clamping force Document: LAT-PR-01967 Section 13 Mechanical Systems 164

GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • GLAST LAT Project CDR/CD-3 Review May 12 -16, 2003 Studies since Delta PDR • CAL-Grid interface shear load capability (cont) • Summary: • A friction joint will prevent bulk slippage of the CAL and maintain the LAT natural frequency. • 89% of fasteners require μ < 0. 2. Plan to run an analysis to show that load redistribution for the remaining 11% does not adversely affect the LAT natural frequency. • GSFC has recommended that a bolted-pinned joint be adopted. – Design implementation study and impact study would be the next step. Document: LAT-PR-01967 Section 13 Mechanical Systems 165